1. Field of the Invention
The present invention relates to quaternary ammonium salts of carboxymethylcellulose. Particularly it relates to those wherein a degree of substitution by carboxymethyl group per anhydrous glucose unit of carboxymethylcellulose (hereinafter referred to as "DS") is from 1.5 or more.
2. Description of the Prior Art
As quaternary ammonium salts of carboxymethylcellulose (hereinafter referred to as "CMC") there have been known the dimethyllaurylcetylammonium salt (West German Pat. No. 1,103,336), trimethyloctadecylammonium salt (U.S. Pat. No. 2,881,074), dodecyldimethyl(3,4-dichlorobenzyl) ammonium salt [Deut. Apotheker-Ztg., 106 (35), 1206-8 (1966)], tetradecylpyridinium salt and cetyltrimethylammonium salt [Pham. Ind., 37, (2), 100, (1976)].
These quaternary ammonium salts of CMC are used to utilize the characteristic properties of the CMC moiety as a soluble high molecular substance as well as the quaternary ammonium moiety. However, DS of CMCs of the above prior salts is believed to be 1.0 or less judging from DS of the commercially available products, while the content of the quaternary ammonium moiety is obliged to be 1.0 or less molecule per anhydrous glucose unit of CMC from the theoretical viewpoint that the quaternary ammonium group can be combined with the carboxymethyl group in the ratio of 1:1. This means that it can not be expected to utilize the characteristic property of the quaternary ammonium moiety to be exerted when it exists in more than 1.0 molecule per anhydrous glucose unit of CMC.
In these known quaternary ammonium salts of CMC, when the molecular weight of the quaternary ammonium moiety is low (e.g., lower alkyl substituted ammonium moiety), they are soluble in water but insoluble in organic solvents, and when it is high, they become insoluble in water and sparingly soluble in polar solvents such as alcohols and acetone and in non-polar solvents such as toluene. Therefore, these salts could not be used for usages to be in the form of solution in organic solvents.